Terminal blocks exist for terminating one or more conductors to a multi-conductor cable, typically comprising a housing of insulating material and screw-operated insulation displacement terminals positioned in cavities of the housing.
An example of a terminal block of that kind is disclosed in U.S. Pat. No. 4,993,966. The terminal block is used for connecting pairs of drop wires to pairs of conductors of a multi-conductor cable, for instance a telephone cable. The connector block comprises a housing having a plurality of apertures therethrough. Individual terminal modules may be inserted into each aperture of the housing in different orientations so that the drop wires can be connected from different directions. Each module has two insulation displacement terminals having slots into which the pairs of insulated drop wires are forced by means of a screw such that the terminals make contact with the conductors of each wire. The opposite ends of the terminals are connected in a conventional manner to pairs of conductors of the multi-conductor cable.
A further example of a known terminal block connecting local cable conductors to a telephone distribution cable is disclosed in U.S. Pat. No. 4,652,071. The block has insulation displacement terminals inserted into a plurality of recesses of an elongated body of insulating material. Connector members are forced into the recesses by a screw mounted in each connector member. To establish contact between an insulated conductor and a terminal, the conductor is inserted into a transverse bore of the connector member which when pushed down by rotating the screw allows the terminal to enter the member and make contact with the conductive core of the conductor. The other ends of the terminals are connected in a conventional manner to the cable conductors.
The connector blocks of the above-identified patents are intended for connecting conductors or wires to one another. They cannot be used for making connection to the conductive traces of printed circuit boards. The insulation displacement terminals of the known terminal blocks each consists of many complicated parts and do not allow for accommodation of more than one conductor. To connect two or more conductors to one terminal, however, is often necessary in establishing connections to printed circuit boards. Prior known terminal blocks for printed circuit boards using screws for clamping the conductive cores of conductors accommodate more than one conductor, but the insulation of the conductors must be stripped off before inserting them into the terminals.
Accordingly, this invention is directed to a terminal block for establishing a connection between multiple conductors and a printed circuit board using insulation displacement terminals which therefore eliminate the need to strip the insulation from the conductor. Furthermore, the terminal block according to the invention has a minimum number of parts with consequent low cost and simple assembly.
In connecting more than one insulated conductor to each terminal, the invention provides that each terminal comprises a first contact member and a second contact member. The first contact member has an upper portion including a transverse opening to accommodate one or more conductors, and a lower portion forming a downwardly extending pin extending through a base portion of an insulative housing and adapted to be inserted in a plated through hole printed circuit board. The second contact member forms a cage which has on its top a threaded bore adapted to accept a screw. The cage has a transverse opening which is adapted to be aligned with the transverse opening of the first contact member when the upper portion of the first contact member is slidably mounted in the second contact member. One of the transverse openings of the first and the second contact member has at least one insulation displacement slot. The screw of the second contact member rests with its end on the upper portion of the first contact member and when rotated forces the openings of the first and the second contact members out of alignment such that the conductors are forced into the insulation displacement slots.
Accordingly the terminals each have only three parts, namely the two contact members and the screw. Any desired number of terminals can be inserted into the base portion of the housing to form a block or module.
When the screw is rotated, the conductors inserted into the transverse openings of the two contact members are each forced into an insulation displacement slot where a secure mechanical and electrical connection is made between the contact members at the edges of the displacement slots and the conductive cores of the conductors.
The insulative housing may include a cover having cavities each for accommodating one terminal and being connectable to the base portion of the housing. Each cavity is provided with a transverse opening formed in one of its sidewalls each opening being aligned with the transverse openings of the first and the second contact members for receiving the conductors. Each cavity further includes an openings on top for accessing the screw. The cover preferably consists of a transparent plastic material such that the terminated conductors may be seen.
Advantageously, the cage-like structure of the second contact member may be formed from a folded metal strip, having end portions spaced apart for slidably accommodating the upper portion of the first contact member. The transverse opening of the first contact member is provided with at least one insulation displacement slot which extends from the opening in an upward direction. The insulation displacement slots may also be provided in the second contact member extending from its transverse opening in a downward direction. It would also be possible to provide both the first and second contact members with insulation displacement slots. If the first contact member is provided with the slots, the electrical resistance between the conductors and the printed circuit board is at a minimum.
One of the walls of the second contact member adjacent the wall containing the transverse opening may be formed so as to provide a horizontal guide surface aligned with the transverse openings of the first and the second contact members and the sidewall openings of the cover for securely guiding the conductors into the openings of the contact members.
While the housing may comprise any number of cavities, a module including two cavities each accommodating one terminal is of advantage in the practice. Several modules of that kind can be arranged side by side on a printed circuit board.